How does skin advertising work on CSMiddler?
As soon as a seller logs in to the marketplace, we present the opportunity to publish one or more skins for sale. In a similar way to the block. The seller's Steam inventory and its contents are retrieved from the Steam API.
Once the ad is published, we show the ad to our tens of thousands of daily web visitors and if the price is fair, someone may choose to buy it. Then we send a notice to the seller that the content of the ad, the digital item, has been purchased. Then the money from the buyer is reserved in "escrow".
As soon as the buyer has created a Steam trade offer to the seller, we send an SMS to the seller about this.
Often just 4 minutes later, the seller has accepted it. We verify it through the Steam API using both parties' Steam Web API keys like a contract. Then we transfer the money from the buyer's escrow to the seller's wallet.
All of this happens in transactions and secure environments that work on an "all or nothing" model. That is, either the buyer gets the skin and the seller gets the money in the same iteration, or nothing happens - for example, if there is a technical error.